Re: Map offsets

["Bäng-ha  " <jpbarda@hotmail.com>]

OK, now you made me curious... I've been thinking a long time about reading 
about ELF, but please tell me what that number indicates, would you?
I'm using gdb-5.0rh-5

----Original Message Follows----
From: Daniel Jacobowitz <drow@mvista.com>
To: Bäng-ha   <jpbarda@hotmail.com>
CC: gdb@sources.redhat.com
Subject: Re: Map offsets
Date: Sat, 9 Mar 2002 11:09:53 -0500
User-Agent: Mutt/1.3.23i

On Sat, Mar 09, 2002 at 03:52:34PM +0000, B?ng-ha ? wrote:
 > Hi!
 >
 > I'm sure this is a rather stupid question, but I'll ask it anyway:
 > I'm debugging a couple of processes under linux, and I want to load the
 > symbols from glibc. Now, the only way I've managed to figure out as to
 > perform the task of finding the base address of libc if to look at the
 > memory maps in /proc/?/maps, whence I get the base address of libc to be
 > e.g. 0x40020000 (this was for mingetty). So naturally, I do 
add-symbol-file
 > /lib/libc-2.2.2.so 0x4002000, but as it turns, it should be loaded
 > 0x4003BCB0, i.e. at an offset of 0x1BCB0 from what /proc says. (I got the
 > exact offset from looking at the dynamically linked function tables and
 > comparing the read function to what was acutally loaded, if that would
 > somehow matter) Anyway, I guess I could live with this small annoyance, 
if
 > it wasn't for that other libs wants to be loaded with other offsets. 
0x1BCB0
 >
 > didn't work with e.g. libresolv. And, I want to know the cause of this as
 > well, of
 > course.
 > So could someone tell me how to get the real offset, because I can't 
imagine
 >
 > that there isn't an error-free way to get the address, right?

objdump -x /lib/libc.so.6:

  10 .text         000e1460  0001d500  0001d500  0001d500  2**4
                   CONTENTS, ALLOC, LOAD, READONLY, CODE

That second number.

This should absolutely not be necessary!  GDB should do it
automatically.  What version of GDB are you using?

--
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer


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